The invention is in the field of automatic mail processing equipment. One portion of the mail handling system in post offices in large cities includes automatic stamp cancelling equipment for envelopes that fall within certain limits as to size standardization. The mail is first hand sorted to eliminate most oversized and undersized envelopes, with the balance being dropped into a 10' long singulator having stationary walls and a moving belt floor. The singulator has periodically extending frictional spring fingers which help to separate side by side and overlapping envelopes so that a single file stream is produced.
At the end of this singulator is a rack into which the single file envelopes are stacked, edgewise, and an automatic cancelling machine draws envelopes individually from one end of the stack and cancels the stamp. The cancelling machine is capable of accepting about 38,000 pieces of mail per hour, but the feeding is inadequate and under ordinary conditions of use, at least partially because of the inadequacy of the current signulator, only 14,000 to 20,000 pieces of mail per hour are cancelled. In addition, failure of the singulator to singulate the letter with 100% accuracy from time to time results in the jamming of the cancelling machine which, although it is being overseen by a postal operator, will ordinarily destroy several envelopes and jam up before there is time to stop the system.
For these reasons there is a need for an improved singulator which, preferably in the same 10' spaces previously allotted to singulation, produces a stream of singulated envelopes with a non-existent, or virtually non-existent singulation failure rate.